Never call qsort on potentially NULL arrays

This extends 62678ded 'efi: never call qsort on potentially
NULL arrays' to all other places where qsort is used and it
is not obvious that the count is non-zero.

5 files changed, 17 insertions, 3 deletions

diff --git a/src/shared/cgroup-show.c b/src/shared/cgroup-show.c
index e971f36190..cc44ab4ea9 100644
--- a/src/shared/cgroup-show.c
+++ b/src/shared/cgroup-show.c
@@ -44,6 +44,8 @@ static void show_pid_array(int pids[], unsigned n_pids, const char *prefix, unsi
         unsigned i, m, pid_width;
         pid_t biggest = 0;
 
+        assert(n_pids > 0);
+
         /* Filter duplicates */
         m = 0;
         for (i = 0; i < n_pids; i++) {
diff --git a/src/shared/conf-files.c b/src/shared/conf-files.c
index 6d99739353..ed4070c662 100644
--- a/src/shared/conf-files.c
+++ b/src/shared/conf-files.c
@@ -127,7 +127,7 @@ static int conf_files_list_strv_internal(char ***strv, const char *suffix, const
                 return -ENOMEM;
         }
 
-        qsort(files, hashmap_size(fh), sizeof(char *), base_cmp);
+        qsort_safe(files, hashmap_size(fh), sizeof(char *), base_cmp);
         *strv = files;
 
         hashmap_free(fh);
diff --git a/src/shared/efivars.c b/src/shared/efivars.c
index c015b16857..f3eb6a6e5d 100644
--- a/src/shared/efivars.c
+++ b/src/shared/efivars.c
@@ -384,8 +384,7 @@ int efi_get_boot_options(uint16_t **options) {
                 list[count ++] = id;
         }
 
-        if (list)
-                qsort(list, count, sizeof(uint16_t), cmp_uint16);
+        qsort_safe(list, count, sizeof(uint16_t), cmp_uint16);
 
         *options = list;
         return count;
diff --git a/src/shared/fileio.c b/src/shared/fileio.c
index 603a1c7b38..733b320388 100644
--- a/src/shared/fileio.c
+++ b/src/shared/fileio.c
@@ -662,6 +662,7 @@ int get_status_field(const char *filename, const char *pattern, char **field) {
         int r;
 
         assert(filename);
+        assert(pattern);
         assert(field);
 
         r = read_full_file(filename, &status, NULL);
diff --git a/src/shared/util.h b/src/shared/util.h
index 26af5b30af..09e556d011 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -772,3 +772,15 @@ bool id128_is_valid(const char *s) _pure_;
 void parse_user_at_host(char *arg, char **user, char **host);
 
 int split_pair(const char *s, const char *sep, char **l, char **r);
+
+/**
+ * Normal qsort requires base to be nonnull. Here were require
+ * that only if nmemb > 0.
+ */
+static inline void qsort_safe(void *base, size_t nmemb, size_t size,
+                              int (*compar)(const void *, const void *)) {
+        if (nmemb) {
+                assert(base);
+                qsort(base, nmemb, size, compar);
+        }
+}